Anatomy of the knee joint
The knee is a hinge joint, the upper and lower leg bones articulate with each other and is nicely cushioned by two little cartilage discs called menisci. The knee is made up of 2 articulating bones (the tibia and femur); they both have cartilage coating the ends to provide a protective cushion with the meniscus acting like a shock absorber.
There are lots of muscles that aid the action of the knee joint and ligaments found in between and on the outside of the joint that help support the movement and stability of the joint – the muscles move our leg bones and the ligaments are like guide wires on a bridge, they allow the joint to move within a certain range safely. All of this amazing structure is then bathed in fluid that nourishes and lubricates the joint.
Funny thing about these two bones, they actually do an additional movement as you bend and stretch your leg…they rotate! The reason for this action is to help put tension on or take tension off of the ligaments around the joint – this helps to support the joint during movement. This rotating action is small, happens within a limited range of movement and is all dependent on what you’re doing. For instance, if you have your feet on the ground, such as doing standing squats, your thigh bone (femur) rotates on a steady lower leg bone (tibia). If you are sitting and extending your legs out (see the video) then your lower legs rotate on a steady thigh bone. A bit complicated but good to be aware of….you can actually feel this subtle movement by standing with your legs parallel apart on the floor and hands on the side of your thigh bones – bend your knees straight forwards (a standing squat) and slowly stretch your legs straight to stand, feel how the thigh bones slightly rotate inwards as you stand tall.
On top of this joint lies a triangular bone called the patella. This little bone acts like a pulley system for our big quad (front thigh) muscles to use. It slides up and down slightly on top of the joint and acts not only like a pulley but provides protection for the joint below it. There are a handful of important ligaments that connect the patella bone to our two big leg bones, and lots of bigger muscles and tendons lying over it again to provide movement and stability for the joint.
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